Weird Cross Section for metastable Indium

Physics Processes, Models and Cross Sections
1

Hi :slightly_smiling_face:,

I’m trying to simulate Indium activation by neutron produced in proton’s accelerator.
I’m using G4_In, QGSP_BIC and G4RadioactiveDecayPhysics (according to this post: Can't get metastable levels of In during run - #2 by civanch )

However, when I launch my simulation with 2.5 MeV neutrons,I ended with more In116[m] or In113[m] than In115[m] ( with a 25 : 2 and a 3:2 ratio) whereas cross section for theses reactions are normally in favor of In115[m] production (and even more for In113[m] given its weak proportion) .

And when I try to add _HP, there is no metastable production.

Thank you!

Thibault

1 Like
2

Here, a macro for example Hadr03 (with QGSP_BIC selected), and the printout.
You can study In113 and In115 separately by changing material.

thibault.mac.txt (312 Bytes)
thibault.out.txt (3.8 KB)

3

Hi ,
I have already tried the Hadr03 and the result is the same,
even in your output file: for 10⁵ incident neutron, In115[336.244]: 3533
Cross section for this reaction is 0.343b
The total cross section is about 1.87b without elastic scattering and 4.96b with it.
So, like all primary particle will interact in material, the final distribution should be according the cross section distribution.
And if we follow this point with 10⁵ primary , we should have for In115m (0.343/1.87)*10⁵=18342 or (0.343/4.96)*10⁵=6915 activated atoms which is about 5 times more than what we can observe.

4

I agree with your analyse. Below, a mail sent to Alberto and Vladimir :

Neutron (2.5 MeV) on In115. QGSP_BIC constructor selected.
The number of created ions (or excited) do not match the cross sections given by G4HadronicProcessStore.

This does not happen with QGSP_BIC_HP. But there is no metastable states created !

thibault.mac.txt (257 Bytes)
thibault.out.txt (2.1 KB)

5

Hi,

I just found that the JEFF 3.3 database (JEFF-3.3) provided by NEA have neutron’s files

These files seems to list all reactions for each particle and giving its cross section.

Maybe is their a way to use this file in Geant4 ?
(other than the converted JEFF to G4NDL because there is no change for metastable creation)

Thibault

6

Hello,

JEFF data for metastable level production may be converted to HP files for In target. You may add these new files to HP data set.

Concerning non-HP model: there are no partial cross sections but transition probabilities for gamma de-excitation and analytical probabilities of other reactions. Here one may check levels and probabilities inside G4LEVELGAMMADATA for In.

VI

7

I tried to add JEFF data but I just ended by changing cross section for inelastic scattering without any change in metastable production.

I also tried using QGSP_BIC physic list with LEND data like this:

  G4VModularPhysicsList* physicsList = new QGSP_BIC;
  physicsList->ReplacePhysics(new G4HadronElasticPhysicsLEND(2,"ENDF/BVII.1"));
  physicsList->ReplacePhysics(new G4HadronPhysicsShieldingLEND(1));
  physicsList->RegisterPhysics(new G4RadioactiveDecayPhysics());

  runManager->SetUserInitialization(physicsList);

But this change also kill the metastable production.

Should I just use QGSP_BIC_HP, retrieving number and energy of incident neutrons on my target, and after the run use tabulated cross section for determining the number of metastable created ?